Gaseous electric discharge device



Aug. 31, 1937.

O. FRITZE El AL GASEOUS ELECTRIC DISCHARGE Filed Aug. 21, 1936 DEVICE INVENTORS Otto Frikze' Alfred Ruktenauer ATTORNEY Patented Aug. 31, 1937 UNITED STATES PATENT OFFICE I 2,091,277 GASEOUS ELECTRIC DISCHARGE DEVICE out Fritze, Berlin, a d Alfred Ruttenauer, Berlin-Halensee, Germany, assignors to General Electric Company, a corporation of New York Application August 21, 1936, Serial No. 97,294 In Germany September I, 1935 2 Claims.

The present invention relates to gaseous electric discharge .devices generally and more particularly the invention relates to such devices having a luminescent material associated therewith 5 which material emits light during the operation of the lamp to complement and supplement the' visible light emitted by the luminescent gaseous The object of the present invention is to pro-.

vide a highly efiicient gaseous electric discharge lamp having glowed zinc silicate associated therewith. Another object of the invention is to provide a lamp of this type which retains its high eficiency for a long useful operating life. A further object of the invention is to provide a gaseous electric discharge lamp having luminescent ma terial associated therewith which may be trans- I ported in'commerce with safety. Further objects and advantages attaching to the device and'to its use and operation may be apparent to those skilled in the art from the following particular description. We have discovered that the grain size of the zinc silicate hasa great influence on the light output of a mercury vapor discharge lamp having a coating of zinc silicate on the container as well as on the loss of emciency of the lamp during the operation thereof. We have discovered; further,

that when the particles of zinc silicatehave a grain size of .between approximately and 100 mu the light output of the lamp is about twice that of similar lamps in which the grain size of 5 the zinc silicate ranges from l mu to 300 mu. The increased light output of /the lamp of the present invention is due to the fact that the elimination or particles having a grain size less than 50 mu reduces the reflection of the light by the 50 luminescent material. Further, when the coating is 'applied to the inner surface of the lamp container the elimination of the zinc silicate particles of less than 50 mu reduces the'loss in light output of the lamp during the operation thereof since the larger particles of the zinc silicate have a It is usually necessary to heat such masmaller surface as compared to their mass than the smaller particles and hence the light converting quality thereof is less impaired by thedischarge'during the operation of the lamp. We

have demonstrated that the light output of a mercury vapor discharge lamp having a coating of zinc silicate on the inner surface of the container thereof in which the grain size of the zinc silicate particles .is greater than 50 mu is three times that of a similar lamp in which an appreciable 'part of the zinc silicate coating consists of particles having a diameter smaller than 50 mu after both lamps have been operating for a period of approximately hours.

The elimination of particl'eshaving a grain size greater than 100 mu is advantageous since particles of larger grain sizes. are apt to drop'off the container wall during transportation of the lamp.

When desired, the particles of a grain size of about 50 to 100 mu are selected by sieving the glowed zinc silicate.

In the drawing accompanying and forming part of this specification an embodiment of the invention is shown in a side elevational, partly sectional view.

Referring to the drawing the lamp comprises an elongated tubular container I having an elec-- trode 4 sealed therein at each end, which electrode 4 is connected to a current lead 3 sealed into the external pinch 2 of the container I. 'Said container 1 has a gaseous atmosphere therein consisting of a starting gas, such as argon, at a pressure of approximately 1 to 10 mm. and a quantity 6 of vapon'zable material therein, such as mercury, the vapor of which emits light during the operation of the device.

Said container i has a luminescent coating '5 of zinc silicate thereon the particles of which have a grain size of approximately 50 to 100 mu. The luminescent material is applied to the inner wall of said container by methods now knownin the 'art, such as by first covering the inner surface of said container l with' a volatilizable binder, such as a mixture of glycerin and alcohol, and then applying the zinc silicate particles, as by dusting, to the binding material.

The binder is then volatilized and'removed from the container I, as by heating and exhausting said container I. The electrodes 4 are electron emitting when heated and consist of a pulverized, sintered mixture of high melting point material, such as tungsten, and a material-having high electron emissivity characteristics, suchas an alkaline earth oxide. I A lamphaving the structure described above is a highly'eiiicint light source, retains its efficiency for a long useful operating life and can be transported in commerce without particles of the luminescent material separating from the container wall,

While we have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its use and operation may be made by those skilled in the art without departing from the spirit and scope of the invention, for example, other types of thermionic electrodes, such as the well known Hull type of hot, electron emitting electrode, or an electrode consisting of a bar or rod of electron emitting, oxide material having a filament of high melting point material, such as tungsten, wrapped around it, are used in place of the electrodes 4, when desired, or cold electrodes are used, when desired.

What we claim as new and desire to secure by Letters Patent of the United States, is:--

1. A gaseous electric discharge lamp device comprising a container, electrodes sealed therein, a gaseous atmosphere therein and a coating of zinc silicate associated with said lamp, said zinc silicate having a grain size from about 50 to 100 2. A gaseous electric discharge lamp device comprising a container, electrodes sealed therein, a gaseous atmosphere therein comprising mercury vapor and a coating of zinc silicate on the inner surface of said container, said zinc silicate having a grain size from about 50 to 100 mu.

OTTO FRITZE. ALFRED RU'I'TENAUER. 

